When you have the right water, setting up your new fish tank is easy—even for beginners! Understanding the difference between tap water and filtered water will help ensure that your fish have a healthy, happy life in their new home.

Aquarium Cleaning Tips

First, you’ve got to get your tank ready. Whether you’re using a newly purchased aquarium, or you’ve gotten one second-hand, a good rinsing with hot water should be enough to prep it for fish. Using cleaning products or soap will only agitate your fish and make the tank a hostile environment for them. Got any white calcium deposits (an annoying side effect of hard water) on your used tank? Just scrape them off the glass with a clean razor blade. (Check out these fish tank cleaning details from Land of Fish if you want the step-by-step process.) After you’ve rinse-cleaned your tank and decorated the bottom with some pebbles or other substrate, you’re ready to fill your tank with the right water. This is the most important step in aquarium set-up, so remember this: Fish don’t like chlorine. Chlorine kills beneficial bacteria in your aquarium. It can also burn your fish’s gills and make it difficult for them to breathe properly. Since our municipal tap water is treated with chlorine, using plain tap water can upset and harm your fish. Leaving fish in untreated tap water can eventually kill them, so be sure to put them in the right water from the start.

The Best Aquarium Water

Chlorine-free, filtered water is the best water for your aquarium because it’s clean and fresh. If your home already has a reverse osmosis (or RO) drinking water system—you’re in luck! An RO system removes chlorine, chloramines, sodium, lead, fluoride, cysts, and just about every other nasty thing from tap water. Your fish will be more than happy to have that kind of filtered water for their home. But before you add fish to RO aquarium water, make sure you give them plenty of time to acclimate. Your fish’s old tank probably had a drastically different pH than what it’ll be moving into. To save your fish from pH shock, you’ll need to test the water in your tank and the fish’s travel baggie. Once you know the difference, you can add a single ½ cup of your RO tank water to the bag. Do this every 15 minutes until you get the levels to match (estimate a .1 pH change each time) to help your fish adjust to their new home. With the right filtered water and some healthy aquarium fish, all that’s left is to keep your tank neat and tidy. Consider adding a filter to your aquarium. Removing or replacing about 20% of the water every week or two can also help. Your fish will be happy to have fresh RO water, and your tank won’t get so cloudy. Beginning aquariums are pretty and fun when you use the right water. Tap water and chlorine are dangerous for your fish, so it’s always better to use RO water and acclimate your fish carefully. If you keep these aquarium tips in mind, we’re sure you and your fish will get along swimmingly!